# Complex number problem

1. May 30, 2005

### floped perfect

If z= CosA+iSinA, express 2/1+z in the form I-Tan(kA).

2. May 30, 2005

### dextercioby

Well,what is that number (2/(1+z)) equal to?

And what do you mean by "I-Tan(kA)"...?

Daniel.

3. May 30, 2005

### floped perfect

where k is a constant and A is the angle from above, it says to express the answer in that form- z is a complex number in polar form.
I tried multiplying the 2/(1+z) by the conjugate (1-z) on the top and bottom but I can't get it into the form 1-Tan(kA).
I think this involves trignometric identities and de Moivre's theorem.

4. Jun 1, 2005

### goldi

you write z as (cosA + i SinA) and multilply the denominator by (1+ CosA --iSinA)...Simplify it...